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Message-ID: <65634d660903141115w7e164134ycece307f041e93a9@mail.gmail.com>
Date: Sat, 14 Mar 2009 11:15:21 -0700
From: Tom Herbert <therbert@...gle.com>
To: David Miller <davem@...emloft.net>
Cc: yanmin_zhang@...ux.intel.com, bhutchings@...arflare.com,
andi@...stfloor.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, herbert@...dor.apana.org.au,
jesse.brandeburg@...el.com, shemminger@...tta.com
Subject: Re: [RFC v2: Patch 1/3] net: hand off skb list to other cpu to submit
to upper layer
On Fri, Mar 13, 2009 at 7:19 PM, David Miller <davem@...emloft.net> wrote:
> From: Tom Herbert <therbert@...gle.com>
> Date: Fri, 13 Mar 2009 17:24:10 -0700
>
>> Enabling HW multi-queue has somewhat higher CPU
>> utilization though, the extra device interrupt load is not coming for
>> free. We actually use the HW multi-queue in conjunction with our
>> software steering to get maximum pps (about 20% more).
>
> This is a non-intuitive observation. Using HW multiqueue should be
> cheaper than doing it in software, right?
>
I suppose it may be counter-intuitive, but I am not making a general
claim. I would only suggest that these software hacks could be a very
good approximation or substitute for hardware functionality. This is
a generic way to get more performance out of deficient or lower end
NICs.
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